Cheng Ying Hsieh

Neuroprotective mechanisms of puerarin in middle cerebral artery occlusion-induced brain infarction in rats

Puerarin, a major isoflavonoid derived from the Chinese medical herb Radix puerariae (kudzu root), has been reported to be useful in the treatment of various cardiovascular diseases. In the present study, we examined the detailed mechanisms underlying the inhibitory effects of puerarin on inflammatory and apoptotic responses induced by middle cerebral artery occlusion (MCAO) in rats. Treatment of puerarin (25 and 50 mg/kg; intraperitoneally) 10 min before MCAO dose-dependently attenuated focal cerebral ischemia in rats. Administration of puerarin at 50 mg/kg, showed marked reduction in infarct size compared with that of control rats. MCAO-induced focal cerebral ischemia was associated with increases in hypoxia-inducible factor-1α (HIF-1α), inducible nitric oxide synthase (iNOS), and active caspase-3 protein expressions as well as the mRNA expression of tumor necrosis factor-α (TNF-α) in ischemic regions. These expressions were markedly inhibited by the treatment of puerarin (50 mg/kg). In addition, puerarin (10~50 μM) concentration-dependently inhibited respiratory bursts in human neutrophils stimulated by formyl-Met-Leu-Phe. On the other hand, puerarin (20~500 μM) did not significantly inhibit the thiobarbituric acid-reactive substance reaction in rat brain homogenates. An electron spin resonance (ESR) method was conducted on the scavenging activity of puerarin on the free radicals formed. Puerarin (200 and 500 μM) did not reduce the ESR signal intensity of hydroxyl radical formation. In conclusion, we demonstrate that puerarin is a potent neuroprotective agent on MCAO-induced focal cerebral ischemia in vivo. This effect may be mediated, at least in part, by the inhibition of both HIF-1α and TNF-α activation, followed by the inhibition of inflammatory responses (i.e., iNOS expression), apoptosis formation (active caspase-3), and neutrophil activation, resulting in a reduction in the infarct volume in ischemia-reperfusion brain injury. Thus, puerarin treatment may represent a novel approach to lowering the risk of or improving function in ischemia-reperfusion brain injury-related disorders.

Experimental and Clinical Pharmacology of Andrographis paniculata and Its Major Bioactive Phytoconstituent Andrographolide

Andrographis paniculata (Burm. F) Nees, generally known as “king of bitters,” is an herbaceous plant in the family Acanthaceae. In China, India, Thailand, and Malaysia, this plant has been widely used for treating sore throat, flu, and upper respiratory tract infections. Andrographolide, a major bioactive chemical constituent of the plant, has shown anticancer potential in various investigations. Andrographolide and its derivatives have anti-inflammatory effects in experimental models asthma, stroke, and arthritis. In recent years, pharmaceutical chemists have synthesized numerous andrographolide derivatives, which exhibit essential pharmacological activities such as those that are anti-inflammatory, antibacterial, antitumor, antidiabetic, anti-HIV, antifeedant, and antiviral. However, what is noteworthy about this paper is summarizing the effects of andrographolide against cardiovascular disease, platelet activation, infertility, and NF-κB activation. Therefore, this paper is intended to provide evidence reported in relevant literature on qualitative research to assist scientists in isolating and characterizing bioactive compounds.

A novel antithrombotic effect of sulforaphane via activation of platelet adenylate cyclase: ex vivo and in vivo studies

Sulforaphane is a naturally occurring isothiocyanate, which can be found in cruciferous vegetables such as broccoli and cabbage. Sulforaphane was found to have very potent inhibitory effects on tumor growth through regulation of diverse mechanisms. However, no data are available concerning the effects of sulforaphane on platelet activation and its relative issues. Activation of platelets caused by arterial thrombosis is relevant to a variety of cardiovascular diseases. Hence, the aim of this study was to examine the in vivo antithrombotic effects of sulforaphane and its possible mechanisms in platelet activation. Sulforaphane (0.125 and 0.25 mg/kg) was effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice. Other in vivo studies also revealed that sulforaphane (0.25 mg/kg) significantly prolonged platelet plug formation in mice. In addition, sulforaphane (15-75 μM) exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen. Sulforaphane inhibited platelet activation accompanied by inhibiting relative Ca(2+) mobilization; phosphorylation of phospholipase C (PLC)γ2, protein kinase C (PKC), mitogen-activated protein kinases (MAPKs) and Akt; and hydroxyl radical (OH(●)) formation. Sulforaphane markedly increased cyclic (c)AMP, but not cyclic (c)GMP levels, and stimulated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, but not ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxal in-1-one), an inhibitor of guanylate cyclase, obviously reversed the sulforaphane-mediated effects on platelet aggregation; PKC activation, p38 MAPK, Akt and VASP phosphorylation; and OH(●) formation. Furthermore, a PI3-kinase inhibitor (LY294002) and a p38 MAPK inhibitor (SB203580) both significantly diminished PKC activation and p38 MAPK and Akt phosphorylation; in contrast, a PKC inhibitor (RO318220) did not diminish p38 MAPK or Akt phosphorylation stimulated by collagen. This study demonstrates for the first time that in addition to it originally being considered as an agent for prevention of tumor growth, sulforaphane possesses potent antiplatelet activity which may initially activate adenylate cyclase/cAMP, followed by inhibiting intracellular signals (such as the PI3-kinase/Akt and PLCγ2-PKC-p47 cascades) and ultimately inhibiting platelet activation. Therefore, this novel role of sulforaphane may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

Andrographolide, a Novel NF-κB Inhibitor, Induces Vascular Smooth Muscle Cell Apoptosis via a Ceramide-p47phox-ROS Signaling Cascade

Atherosclerosis is linked with the development of many cardiovascular complications. Abnormal proliferation of vascular smooth muscle cells (VSMCs) plays a crucial role in the development of atherosclerosis. Accordingly, the apoptosis of VSMCs, which occurs in the progression of vascular proliferation, may provide a beneficial strategy for managing cardiovascular diseases. Andrographolide, a novel nuclear factor-κB inhibitor, is the most active and critical constituent isolated from the leaves of Andrographis paniculata. Recent studies have indicated that andrographolide is a potential therapeutic agent for treating cancer through the induction of apoptosis. In this study, the apoptosis-inducing activity and mechanisms in andrographolide-treated rat VSMCs were characterized. Andrographolide significantly induced reactive oxygen species (ROS) formation, p53 activation, Bax, and active caspase-3 expression, and these phenomena were suppressed by pretreating the cells with N-acetyl-L-cysteine, a ROS scavenger, or diphenylene iodonium, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) inhibitor. Furthermore, p47phox, a Nox subunit protein, was phosphorylated in andrographolide-treated rat VSMCs. However, pretreatment with 3-O-methyl-sphingomyelin, a neutral sphingomyelinase inhibitor, significantly inhibited andrographolide-induced p47phox phosphorylation as well as Bax and active caspase-3 expression. Our results collectively demonstrate that andrographolide-reduced cell viability can be attributed to apoptosis in VSMCs, and this apoptosis-inducing activity was associated with the ceramide-p47phox-ROS signaling cascade.

Chondroprotective role of sesamol by inhibiting MMPs expression via retaining NF-κB signaling in activated SW1353 cells.

Overexpression of matrix metalloproteinases (MMPs) is a major pathological factor causing cartilage destruction in osteoarthritis (OA). This study aimed to investigate the effects and mechanisms of sesamol on expression of MMPs in activated chondrosarcoma cells. Sesamol significantly attenuated TNF-α- and IL-1β-induced gelatinolysis and expression of MMP-9 in a concentration-dependent manner in SW1353 cells. Additionally, both MMP-1 and -13 stimulated by PMA were inhibited by sesamol. On the other hand, the NF-κB signaling activation through IκB-α degradation was restored by sesamol under TNF-α or PMA stimulation. Furthermore, this bioactive compound exerted the reduction on phosphorylation of ERK1/2 or p38 MAPKs after either PMA or IL-1β stimulation. This study also evaluated whether sesamol down-regulates MMP expression in the joint cartilage of monosodium iodoacetate (MIA)-induced OA in rats. Sesamol prevented the expression of MMP-1 and -9 in the cartilage of MIA-induced OA in rats. The results of this study demonstrate that sesamol inhibits cytokine- or PMA-induced MMPs expression through the signal pathways of either NF-κB or ERK/p38 MAPKs down-regulation. This study also showed that sesamol attenuates destructive factor expression in vivo, providing a potential strategy for the chondroprotective therapy in OA.

Prevention of arterial thrombosis by nobiletin: in vitro and in vivo studies.

Nobiletin, a bioactive polymethoxylated flavone isolated from citrus fruits, has been proven to prevent cancer and inflammation. Dietary flavonoids have been shown to reduce the risk of cardiovascular diseases (CVDs), and platelet activation plays a crucial role in CVDs. This study investigated the effect of nobiletin on platelet activation in vitro and in vivo. Nobiletin (10-30μM) inhibited collagen- and arachidonic acid-induced platelet aggregation in washed human platelets, but it did not inhibit platelet aggregation induced by other agonists such as thrombin and 9,11-dideoxy-11α,9α-epoxymethanoprostaglandin. Nobiletin inhibited the phosphorylation of phospholipase PLCγ2, protein kinase PKC, Akt and mitogen-activated protein kinase MAPKs in collagen-activated human platelets and markedly reduced intracellular calcium mobilization and hydroxyl radical (OH(·)) formation. Nobiletin did not affect either phorbol-12,13-dibutyrate-stimulated PKC activation or platelet aggregation. In addition, neither SQ22536, an adenylate cyclase inhibitor nor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a guanylate cyclase inhibitor, significantly reversed the nobiletin-mediated inhibition of platelet aggregation. Moreover, nobiletin substantially prolonged the closure time in whole blood according to platelet function analysis and increased the occlusion time of thrombotic platelet plug formation in mice. In conclusion, this study demonstrates for the first time that, in addition to being a potential agent for preventing tumor growth and inflammation, nobiletin exhibits potent antiplatelet activity, which initially inhibits the PLCγ2/PKC cascade and hydroxyl radical formation, subsequently suppresses the activation of Akt and MAPKs and ultimately inhibits platelet activation. Our study suggests that nobiletin represents a potential therapeutic agent for preventing or treating thromboembolic disorders.

Andrographolide induces vascular smooth muscle cell apoptosis through a SHP-1-PP2A-p38MAPK-p53 cascade

The abnormal growth of vascular smooth muscle cells (VSMCs) is considered a critical pathogenic process in inflammatory vascular diseases. We have previously demonstrated that protein phosphatase 2 A (PP2A)-mediated NF-κB dephosphorylation contributes to the anti-inflammatory properties of andrographolide, a novel NF-κB inhibitor. In this study, we investigated whether andrographolide causes apoptosis, and characterized its apoptotic mechanisms in rat VSMCs. Andrographolide activated the p38 mitogen-activated protein kinase (p38MAPK), leading to p53 phosphorylation. Phosphorylated p53 subsequently transactivated the expression of Bax, a pro-apoptotic protein. Transfection with pp2a small interfering RNA (siRNA) suppressed andrographolide-induced p38MAPK activation, p53 phosphorylation, and caspase 3 activation. Andrographolide also activated the Src homology 1 domain-containing protein tyrosine phosphatase (SHP-1), and induced PP2A dephosphorylation, both of which were inhibited by the SHP-1 inhibitor sodium stibogluconate (SSG) or shp-1 siRNA. SSG or shp-1 siRNA prevented andrographolide-induced apoptosis. These results suggest that andrographolide activates the PP2A-p38MAPK-p53-Bax cascade, causing mitochondrial dysfunction and VSMC death through an SHP-1-dependent mechanism.

Inhibition of vascular smooth muscle cell proliferation by the vitamin E derivative pentamethylhydroxychromane in an in vitro and in vivo study: pivotal role of hydroxyl radical-mediated PLCγ1 and JAK2 phosphorylation

Abnormal proliferation of vascular smooth muscle cells (VSMCs) plays an important role in the development of cardiovascular diseases. PMC (2,2,5,7,8-pentamethyl-6-hydroxychromane) is the most potent hydrophilic derivative of vitamin E. In this study, we investigated the mechanisms of PMC inhibition of VSMC proliferation in vitro and in vivo. PMC (20 and 50 microM) obviously suppressed proliferation of PDGF-BB-stimulated cells, but not resting cells, and arrested cell cycle progression at the G(2)/M phase. A significant reduction in neointimal formation in carotid arteries was observed in PMC (5mg/kg/day)-treated rats after balloon angioplasty. Activation of STAT3, JAK2, PLCgamma1, PKCdelta, and ROS, but not ERK1/2, AKT, or PKCalpha, was markedly inhibited by PMC in PDGF-BB-stimulated VSMCs. Deferoxamine and PMC significantly inhibited the phosphorylation of PLCgamma1 and JAK2 and arrested cell cycle progression at the G(2)/M phase. These events, however, were reversed in the presence of Fe(2+). Moreover, PMC directly inhibited hydroxyl radical formation in both the Fenton reaction and VSMCs according to an electron spin resonance study. In conclusion, this study demonstrates for the first time that PMC inhibits VSMC proliferation in vitro and balloon injury-induced neointimal formation in vivo. The inhibitory mechanism of PMC may involved the inhibition of hydroxyl radical-mediated PLCgamma1-PKCdelta and JAK2-STAT3 activation and causes cell cycle arrest at the G(2)/M phase. PMC treatment may represent a novel approach for lowering the risk of or improving function in abnormal VSMC proliferation-related vascular diseases.

Andrographolide inhibits nuclear factor-κB activation through JNK-Akt-p65 signaling cascade in tumor necrosis factor-α-stimulated vascular smooth muscle cells.

Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Andrographolide is the most active and critical constituent isolated from the leaves of Andrographis paniculata, a herbal medicine widely used for treating anti-inflammation in Asia. In this study, we investigated the mechanisms of the inhibitory effects of andrographolide in vascular smooth muscle cells (VSMCs) exposed to a proinflammatory stimulus, tumor necrosis factor-α (TNF-α). Treating TNF-α-stimulated VSMCs with andrographolide suppressed the expression of inducible nitric oxide synthase in a concentration-dependent manner. A reduction in TNF-α-induced c-Jun N-terminal kinase (JNK), Akt, and p65 phosphorylation was observed in andrographolide-treated VSMCs. However, andrographolide affected neither IκBα degradation nor p38 mitogen-activated protein kinase or extracellular signal-regulated kinase 1/2 phosphorylation under these conditions. Both treatment with LY294002, a phosphatidylinositol 3-kinase/Akt inhibitor, and treatment with SP600125, a JNK inhibitor, markedly reversed the andrographolide-mediated inhibition of p65 phosphorylation. In addition, LY294002 and SP600125 both diminished Akt phosphorylation, whereas LY294002 had no effects on JNK phosphorylation. These results collectively suggest that therapeutic interventions using andrographolide can benefit the treatment of vascular inflammatory diseases, and andrographolide-mediated inhibition of NF-κB activity in TNF-α-stimulated VSMCs occurs through the JNK-Akt-p65 signaling cascade, an IκBα-independent mechanism.

Platonin inhibited PDGF-BB-induced proliferation of rat vascular smooth muscle cells via JNK1/2-dependent signaling

Aim:To examine the inhibitory actions of the immunoregulator platonin against proliferation of rat vascular smooth muscle cells (VSMCs).Methods:VSMCs were prepared from the thoracic aortas of male Wistar rats. Cell proliferation was examined using MTT assays. Cell cycles were analyzed using flow cytometry. c-Jun N-terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, AKT, and c-Jun phosphorylation or p27 expression were detected using immunoblotting.Results:Pretreatment with platonin (1–5 μmol/L) significantly suppressed VSMC proliferation stimulated by PDGF-BB (10 ng/mL) or 10% fetal bovine serum (FBS), and arrested cell cycle progression in the S and G2/M phases. The same concentrations of platonin significantly inhibited the phosphorylation of JNK1/2 but not ERK1/2 or AKT in VSMCs stimulated by PDGF-BB. Furthermore, platonin also attenuated c-Jun phosphorylation and markedly reversed the down-regulation of p27 expression after PDGF-BB stimulation.Conclusion:Platonin inhibited VSMC proliferation, possibly via inhibiting phosphorylation of JNK1/2 and c-Jun, and reversal of p27 down-regulation, thereby leading to cell cycle arrest at the S and G2/M phases. Thus, platonin may represent a novel approach for lowering the risk of abnormal VSMC proliferation and related vascular diseases.